Motor control system



April 3, 1934. w EASTWOOD 1,953,158

MOTOR CONTROL SYSTEM Filed May 8, 1930 8 Sheets-Sheet l FIGJ.

INYENTOR.

April 3, 1934. w EASTWOOD 1,953,158

MOTOR CONTROL SYSTEM Filed May 8, 1930 6 Sheets-Sheet 2 INVEN TOR.

Mm 5W.

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April 3, 1934. w. EASTWOOD 1,953,158

MOTOR CONTROL SYSTEM Filed May 8, 1930 6 Sheets-Sheet 5 FIGAL. FIGJ).

April 3, 1934.

W. EASTWOOD MOTOR CONTROL SYSTEM Filed May 8, 1930 6 Sheets-Sheet 4INVENTOR.

April 3, 1934. w. EASTWOOD MOTOR CONTROL SYSTEM Filed May 8, 1930 6Sheets-Sheet 5 FIG. 7.

i/l4 A April 3, 1934. w. EASTWOOD 1,953,158

MOTOR CONTROL SYSTEM Filed May 8, 1930 6 Sheets-Sheet 6 Frail.

m WW4 m a I W Patented Apr. 3, 1934 i "rA'rss PATENT orries MOTORCONTROL SYSTEM Application May 8, 1930, Serial No. 450,783 In GreatBritain May 11, 1929 6 Claims.

This invention relates to motor control gear for use where more than onemotor is employed. In certain classes of machinery two or more motorsare mounted on one machine for performing difierent operations, and eachmotor has been provided with separate non-automatic or automatic controlequipment, such equipment in the latter form being operated by means or"push buttons, or small master switches. For example, on a radialdrilling machine a motor is often used to drive the spindle and aseparate motor is often used to lift and lower the radial arm. Theaforesaid push buttons or master switches, being small. can be mountedon the spindle slide of the maq chine in the most accessible position,the panel or panels containing the automatic control equipment beingmounted elsewhere, generally on some other part of the machine. Theautomatic control equipment is a comparatively expensive piece ofapparatus and when a number or these are employed on one machine tocontrol a number of motors the cost of that machine becomes verymaterially increased, and in some cases prohibitive. The presentinvention for its ob ject to simplify the electrical control equipmentwhen more than one motor is used on the machine and when these are notrequired to be running together or at the same time so that very littleadditional cost would be incurred beyond what is ordinarily necessary tofit up a single motor with an electrical control equipment.

In the accompanying drawings: Fig. 1 is a diagram showing two singlespeed 3 reversible motors controlled by one set of contactor equipmentgoverned by a master switch.

Fig. 2 is a longitudinal section, and Fig. 3 a plan of the master switchused in the diagram shown in Fig. 1. Fig. 4 is a transverse sectiontaken approximately on line 4-4 of Fig. 2.

Fig. 5 is a diagram showing the arrangement of the slots in which theswitch lever works.

Fig. 6 is a diagram showing a two-speed re- A versible motor and asingle speed reversible motor controlled by one set of contactorequipment governed by a master switch.

Fig. 7 is a longitudinal section and Fig. 8 a plan of the master switchused in Fig. 6.

Fig. 9 is a transverse section taken approximately on line 99 of Fig. 6.

Fig. 10 is a diagram showing the arrangement of the slots in which theswitch lever works, and

Fig. 11 is a wiring diagram which can be adopted when both motors are ofthe squirrel cage type.

Fig. 1 shows two motors A, B for use on a three phase supply, the motorA being shown as a slip ring motor and the motor B as a squirrel cagemotor, although by modifying the connecdesired.

tions either motor could be of either type. In applying the inventiontoaradial drill, for example, the motor A may be .used for driving thespindle in a forward and reverse direction and the motor B for raisingand lowering the radial arm. The portion of the master switch thatcontrols the operation of the contactor equipment comprises a drumsector C electrically connected with a supply main M and adapted to bemoved into and out of contact with two contacts 0, c situated atopposite sides of the drum. The contacts c are electrically connectedwith a stator contactor comprising an operating coil D and a triple polecontactor switch of which the member d is connected on one side to thesupply main M and on the other side to a drum sector E of the masterswitch which together with a similar sector E can be moved in a rotaryor endwise direction, or'both, to make contact with one or other of fourcross connected contacts b o 0. a, the terminals b b being connectedwith corresponding terminals b b of the elevating motor stator, and theterminals a a with corresponding terminals a a of the slip ring motorstator. These connections enable either the motor A or B to be connectedtothe supply wires from the contactor equipment and also enable theselected motor to run in either direction as The member d of thecontactor switch is connected on the one side with the supply main M andon the other side with the drum sector E The member (1. of the contactorswitch is connected on the one side with the supply main M and on theother side is connected in common to one terminal a o f the slip ringmot-or stator and one terminal b of the elevating motor stator. Eachtime the contactor switch closes, it opens a switch fthat is connectedwith a pick-up coil F appertaining to a relay which controls the openingand closingof two contacts f F. A further contactor comprises anoperating coil G and double pole contactor switch, the two members g, gof which are connected together on one side and also to one terminal a!of the motor winding and" to one end of one phase of the rotor startingresistance A appertaining to the slip ring motor A. Theother side ofswitch member g is connected tonne end of another phase of theresistance Alland to oneterminal a of the rotor. The other side of theswitch member g is in like manner connected to one end of one phase ofthe resistance A and to one terminal a of "the rotor, ,On the relay oneside of each of the contacts I I is connected directly to one ofthesupply; mains .M and the contact f is connectedon the othergside tothe side of the stato'rswitch d which-is inelectrical connection withthe commutator drum sector E. Contact I on the other side is connectedto the operating coil G' which is in turn connected to the commutatordrum sector E The relay has a series wound coil I connected to the starpoint a of the resistance A In the switch shown in Figs. 2 to 5, Cindicates the drum sector which corresponds to that shown in the diagramand c, 0 indicate the spring contacts. The drum sector C is rigidlyfixed on a shaft H that is rotatably mounted in bearings h in a casing hThe shaft H is formed with a square portion M, Fig. 4 on which isslidably mounted a tube 71. enclosed within an insulating tube 11*, andclamped or otherwise fixed on such insulating tube are drum sectors E, Ewhich correspond to those shown on the diagram, and operate inconjunction with the spring contacts b b a a. Fixed to the square k andinsulated therefrom is a hand lever h which works in a H shaped slot,Fig. 5 for imparting a rotary motion to the shaft H and a rotary orendwise movement of both to the square tube k which carries the drumsectors E, E. It indicates a spring which returns the hand lever h to aneutral positon when it has been moved to any of the positions P P P P PP indicated in Fig. 5. If the handle is moved into position Pconnections will be such that the slip ring motor stator is connected tothe main supply lines Whenever the main stator contactor on the panel isclosed; the direction moreover will be such as to cause the motor to runin a clockwise direction. Before the stator contactor can close,however, the sector drum C must make contact with the sping fingers 0This will cause the relay to close the contact 1 Simultaneously with thedrum sector C making contact with the spring finger c it is also makingcontact with the spring finger c and completes a circuit from theoperating coil D of the main stator contactor switch and through thecontact I on the relay, and thus allows the stator contactor to close.When a turning movement is imparted to the drum sector C a correspondingturning movement is simultaneously imparted to the drum sectors E, E butthe drum sector C is so arranged as to make a contact with the fingersc, c at a later period of time than the drum sectors E, E make contactwith the stator connections a a When the stator contactor closes itopens the contact I thus breaking the circuit of the relay pick-up coilF. The relay is however operated by the series wound coil which isconnected in the rotor circuit of the motor A. As soon as the statorcontactor is closed current will begin to flow in the rotor circuit ofthe motor A and also in the series coil f of the relay. After thebreaking of the pick-up circuit above referred to the relay will be heldby the series wound coil 1 until the curent has fallen to somepredetermined value at which point the tension of the relay contactorwill overcome the pull of the series coil 1 and contact I will be openedand contact I closed. This completes the circuit of the rotor contactorthat is actuated by the coil G. This contactor then closes, cutting outthe rotor resistance A and leaving the motor running at full speed, andin the desired direction. If the switch lever h is moved to the ofiposition shown at P Fig. 5 the operating currents for the variouscontactors are interrupted thus allowing the contactor switches to openand cut off the current to the motor. If the switch lever 11. is movedto the position marked P the above sequence of operations is carried outbut the connections are now reversed so that the motor A revolves in acounter-clockwise direction. When the switch lever is moved into eitherof positions P, P the elevating motor B will be running in either aclockwise of counter-clockwise direction of rotation, 15' being the off"position. Provision against switching on the elevating motor B when theradial arm is locked on the column may be obtained mechanically orelectrically as desired. In the mechanical construction shown in Figs. 2and 4 the operating lever h= is connected with a metal guard J which isconstrained to move with the lever 11 Attached to this guard is a bolt7'. Connected to the locking shaft (not shown) on the machine is a plate7' that is pivotally mounted on a bush 1' the arrangement being suchthat when the locking shaft is rotated into its locking position itsconnection with the plate 7' moves the latter into such a position thatthe bolt 7' cannot be moved in an endwise direction, thus preventing thehand lever h from being put into the ele vating slot P P P It is thusimpossible for the elevating motor B to be switched into circuit whenthe radial arm is locked. Also if the hand lever h should be in theelevating slot the bolt i interferes with the movement of the plate 9'and thus renders it impossible to lock up the radial arm on the pillar.This can therefore only be effected by moving the switch handle h intothe slot P P P A method of obtaining the above result electricallyconsists in mounting a drum sector C in such manner that it can move inan endwise direction with the drum sectors E, E see Figs. 6 and 7. Theportion marked K constitutes the interlock and comprises a member thatis rotatably mounted about the shaft H in Fig. '7. This member isconnected by the plate It with an arm mounted on the locking shaft (notshown) in such manner as to open contact whenever the radial arm islocked on the pillar. The diagram shown in Fig. 6, and the switch shownin Figs. 7 to 9 are the same as those described with reference to Figs.1 to 4 with the exception that the motor A has a double stator windingto give two speeds in either direction, the 'drum sectors and springcontacts are increased accordingly, and the gate in which the switchhandle works has three slots for such handle to work as shown in Fig.10, the various positions of the switch handle being indicated at P P PP P P, P". In either of the spindle motor slots P P P P" the controlequipment will function irrespective of the interlock K whether same isopened or closed, but when the lever is in the slot P P which controlsthe elevating motor, the circuit from C to the relay coil F isinterrupted or made by the interlock before the elevating motor can beswitched into circuit. The various positions obtained with the switchare as follows:

P forward slow" P reverse slow" P forward fast" P reverse fast 2 speedspindle motor running and out of contact with two contacts 0 situated atopposite sides of the drum. The contacts c are electrically connectedwith a stator contactor comprising an operating coil D and a triple polecontactor switch of which the member d is connected on one side of thesupply main M and on the other side to a drum sector E of the masterswitch which together with a similar sector E can be moved in a rotaryor endwise direction, or both to make contact with one or other of fourcross connected contacts b b a a the terminals b b being connected withcorresponding terminals 12 b of the motor B and the terminals a a withcorresponding terminals a a of the motor A.

Assuming the drum sectors E, E to be in the full line position shown onthe diagram, if the operating lever 71. is moved to the positionindicated at P in Fig. 5, E will make contact with b and E will makecontact with b This will connect the stator mains through to thecontactor switch. As the lever h is moving to the position P C will makecontact with c. This completes the circuit of the operating coil Dthereby closing the contact and switching on the current. Theconnections may be such that the motor B will revolve in, say forexample, a counter-clockwise direction. If the lever h is brought to theoff position indicated by P in Fig. 5 the operating coil circuit of thecontactor will first be broken and the contactor will open the circuit,cutting off the supply of current to the motor B. By the time that thelever reaches the off position, contacts E and E will have brokencontact with b b If the lever is moved to the position indicated by P inFig. 5 E will make contact with the finger b and E will make contactwith the finger b and as the lever reaches the position P C will makecontact with the finger c and again complete the operating coil circuitof the contactor. When the latter closes, the current is again switchedon to the motor, but in this case the connections will be such as torotate the motor in a clockwise direction. A similar sequence of eventswill follow if the lever is moved through the gate into the positions PP P but this time the motor A will be caused to operate in either aclockwise or counter-clockwise direction as desired.

The invention hereinbefore described is equally applicable to any knownmethod of starting direct current or alternating current motors whetherby non-automatic or automatic starters and whether the motors arereversible or nonreversible, and it is also capable of being used withvariable speed direct current and alternating current motors, and alsowith multispeed alternating current motors.

What I claim as my invention and desire to secure by Letters Patent inthe United States 1s:

1. In a motor control system, the combination of a plurality of motors,a single contactor mechanism that is common to all said motors and asingle master controller for selectively switching said contactormechanism into control of any one of said motors, whereby any motor canbe operated independently of the other motors in any order irrespectiveof sequence.

2. In a motor control system, the combination of a plurality of motors,a single contactor mechanism that is common to all said motors and asingle master controller for selectively switching said contactormechanism into control of any one of said motors, whereby any motor canbe operated independntly of the other motors, said master controllercomprising means for controlling the operation of said contactormechanism in any order irrespective of sequence.

3. In a motor control system, the combination of a plurality of motors,a single contactor mechanism that is common to all said motors and asingle master controller for selectively switching said contactormechanism into control of any one of said motors, whereby any motor canbe operated independently of the other motors, said master controllercomprising means whereby the direction of rotation of any motor may becontrolled.

4. In a motor control system, the combination of a plurality of motors,a single contactor mechanism that is common to all said motors and asingle master controller for selectively switching said contactormechanism into control of any one of said motors, whereby any motor canbe operated independently of the other motors, said master controllercomprising means for controlling the operation of said contactormechanism and means whereby the direction of rotation of any motor maybe controlled.

5. In a motor control system, the combination of a plurality of motors,a single contactor mechanism that is common to all said motors, and asingle master controller for selectively switching said contactormechanism into control of any one of said motors, whereby any motor canbe operated independently of the other motors, said master controllercomprising means operative when any motor is in operation for preventingsimultaneous operation of the other motors.

6. In a motor control system, the combination of a single speed motorand a variable speed motor, a single contactor mechanism that is commonto both of said motors, a single master controller for selectivelyswitching said contactor mechanism into control of either of said motorswhereby either motor can be operated independently of the other motor,said master controller comprising means for controlling the operation ofsaid contactor mechanism whereby the direction of rotation of eithermotor may be controlled and means whereby the speed of the variablespeed motor may be varied.

WALTER EASTWOOD.

